Possibility of single stroke engine.

Discussion in '2-Stroke Aircaft Engines' started by Ethan Appleton, Jun 17, 2019.

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  1. Jun 18, 2019 #21

    Swampyankee

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    I think they built some wave rotor machines as superchargers. I've not paid much attention to wave rotors -- sometimes they seemed like a solution in search of a problem.
     
  2. Jun 18, 2019 #22

    wsimpso1

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    In our customary two- and four-strokes, the engine is the big pump, moving the spent charge out, moving the new charge in, compressing it nearly adiabatically, then after the fuel is burned, expanding the charge nearly adiabatically.

    Your idea, well, it is still a two stroke (once down, then back up per cycle, two strokes). Now let's get into the other topics...
    • The compressor has to produce gas volumes and pressures in the combustion chamber similar to what we get now.
    • When you open the intake valve with the piston near TDC, the compressed air will expand across the valve, losing some energy. This is pumping losses;
    • You will have to make the compressor bigger than the combustion chamber system to actually get to efficient combustion chamber pressures;
    • The vacuum pump for the exhaust will have to handle more volume than at the intake. You added fuel to the air that went in and burned it, so now you have more mass of gas, converted to smaller molecules and so converted to more moles than went in making for more volume at atmospheric pressure, raised its temperature making for more volume. The pump won't have to be as strong, but it sure will have more volume;
    • So, instead of letting a single pumping chamber do the pumping in and compressing and pumping out, you will have a charge pump that goes to really high pressures, a power cylinder, and a really large evacuation pump and all three have to run in concert to make the engine run.
    Wanna bet you will need to run it up into the operating range just to get it to be self sustaining? If idle power is 40% rpm, like jet engines, you will have fun managing this beast on the ground because the prop is then running at 16% torque and thrust when you are trying to taxi...

    Speaking of jet engines, they do run a big compressor on the inlet, but they do not have a evacuator on the outlet and burn fuel continuously...

    If you want to play with single stroke heat engines, the only ones I know of are kind of difficult to operate continuously. They throw away the piston on each stroke, burn fuel that runs around $20 a pound, get dirty to the point of needing cleaning every couple hundred firing strokes... Go a little more primitive and they become two-strokes, as the piston has to go both ways down the bore before being lost and they need cleaning about every 3-10 firing strokes. We are talking guns here...

    Billski
     
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  3. Jun 18, 2019 #23

    pictsidhe

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    I just read back and saw a posts that I missed, I think we're getting trolled...
     
  4. Jun 18, 2019 #24

    BBerson

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    Could inject liquid air and fuel at TDC (and BDC if double acting). Or just at TDC with the return stroke doing nothing but some lubrication.
     
  5. Jun 18, 2019 #25

    mcrae0104

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    I don't know about that, but a one-stroke engine sounds a lot like one hand clapping...
     
  6. Jun 19, 2019 #26

    TFF

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  7. Jun 19, 2019 #27

    Swampyankee

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    Well, the first internal combustion engines did use gunpowder...
     
  8. Jul 9, 2019 #28

    Tiger Tim

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    Even then the piston has to come back and get reset for the cycle, meaning the cycle has to have an even number of strokes. A guess a turbine would be a sort of one-stroke engine?
     
  9. Jul 10, 2019 #29

    TFF

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    A turbine is a constant stroke engine. I figure a rocket would be the closest by definition to one stroke.
     
  10. Jul 10, 2019 #30

    mm4440

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    A cannon is a single stroke engine if you do not consider loading it a stroke. Throwing the piston away each power stroke makes it impractical.
     
  11. Jul 10, 2019 #31

    choppergirl

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    I do at least 3 impossible things before breakfast.

    [​IMG]

    A cylinder, capped on both ends, with a spark plug on both ends, and a piston in center.

    Blast on left side, piston moves right, and compresses mixture on right.

    Blast then on right side, piston moves left, and compresses mixture on left.

    Repeat, over and over again, back and forth. Power on all strokes with one piston.

    Blue dot, in case you didn't guess, extends out slot in side of cylinder barrel on both sides and is where you extract power from.

    Of course, add cooling fans, or water jacket, ports for premix (lubricating oil and fuel), carb, exhaust, and other supporting hardware and electrics, not drawn on purpose, so that you can see piston action and motion without any more chartfunk.

    I wouldn't doubt some Choo Choo Trains in the far distant past used this design, only with steam pressure, not dino juice explosions. So keep that in mind before you run down to the patent office with my diagram in hand still hot off your lasar printer drum.
     
    Last edited: Jul 10, 2019
  12. Jul 10, 2019 #32

    nerobro

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    Still "at least" two stroke. Opposed piston engines have been built.
     
  13. Jul 10, 2019 #33

    mm4440

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    Search free piston engines.
     
  14. Jul 11, 2019 #34

    Swampyankee

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    Search “double-acting engine”
     
  15. Jul 11, 2019 #35

    mcrae0104

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    Blasting suffers considerably without an intake stroke. But perhaps this is an opposed two stroke?
     
  16. Jul 11, 2019 #36

    pictsidhe

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    That's a twin cylinder engine with connected pistons. Each half fires for half the time. It spends the other time going the other way.
    That arrangement is called a 'double acting cylinder' very popular in hydraulics and pneumatics.
    A great number of steam engines used double acting cylinders.
     

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